CPP File Handling & Standard Template Library (STL) 3

Question 1

What is the effect of opening a file with std::ios::app mode?

Accepted Answer

All writes go to the end of the file regardless of seekp()

Answer

In append mode, every write operation automatically moves the put pointer to end-of-file before writing.

Question 2

Which STL container adaptor uses a std::deque as its default underlying container?

Accepted Answer

Both std::stack and std::queue

Answer

Both std::stack and std::queue default to std::deque as their underlying container.

Question 3

What does std::lower_bound() return when no element satisfies the condition?

Accepted Answer

The end iterator of the range

Answer

std::lower_bound returns the end iterator if all elements are less than the value.

Question 4

Which method checks whether a std::fstream has reached end-of-file?

Accepted Answer

std::fstream::eof()

Answer

eof() returns true when the eofbit is set, indicating end-of-file has been reached.

Question 5

What is the time complexity of std::list::splice()?

Accepted Answer

O(1)

Answer

std::list::splice() moves elements between lists in O(1) by relinking pointers.

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